/*=====================================================================*
 *                   Copyright (C) 2011 Paul Mineiro                   *
 * All rights reserved.                                                *
 *                                                                     *
 * Redistribution and use in source and binary forms, with             *
 * or without modification, are permitted provided that the            *
 * following conditions are met:                                       *
 *                                                                     *
 *     * Redistributions of source code must retain the                *
 *     above copyright notice, this list of conditions and             *
 *     the following disclaimer.                                       *
 *                                                                     *
 *     * Redistributions in binary form must reproduce the             *
 *     above copyright notice, this list of conditions and             *
 *     the following disclaimer in the documentation and/or            *
 *     other materials provided with the distribution.                 *
 *                                                                     *
 *     * Neither the name of Paul Mineiro nor the names                *
 *     of other contributors may be used to endorse or promote         *
 *     products derived from this software without specific            *
 *     prior written permission.                                       *
 *                                                                     *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND              *
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,         *
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES               *
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE             *
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER               *
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,                 *
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES            *
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE           *
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR                *
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF          *
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 *                                                                     *
 * Contact: Paul Mineiro <paul@mineiro.com>                            *
 *=====================================================================*/

#include "estep.h"
#include "normalize.c"
#include "prating.c"

static const float log1mepsilon = -0.000010000050000333336;/* log (0.99999) */
static const float logepsilon = -11.512925464970228;       /* log (0.00001) */

float
estep (const float*               loga,
//       unsigned int               n_workers,
       unsigned int               rank,
//       const float*              gamma,
       const float*               logbeta,
       unsigned int               n_images,
       const float*               c,
       unsigned int               n_labels,
       const float*               d,
       float*                     pz,
       const float*               priorz,
       const int*                 clamp,
       Rating*                    ratings,
       unsigned int               n_ratings)
{
  float logpriorz[n_labels];
  float log_n_labels_m1 = (n_labels < 2) ? 0 : log (n_labels - 1);

  for (unsigned int i = 0; i < n_labels; ++i)
    {
      logpriorz[i] = log (priorz[i]);
    }

  for (unsigned int i = 0; i < n_images; ++i)
    {
      if (clamp[i] < 0 || n_labels < 2)
        {
          memcpy (pz + i * n_labels, logpriorz, n_labels * sizeof (pz[0]));
        }
      else
        {
          for (unsigned int j = 0; j < n_labels; ++j)
            {
              if (((unsigned int) clamp[i]) == j)
                {
                  pz[i * n_labels + j] = log1mepsilon;
                }
              else
                {
                  pz[i * n_labels + j] = logepsilon - log_n_labels_m1;
                }
            }
        }
    }

  for (unsigned int i = 0; i < n_ratings; ++i)
    {
      for (unsigned int j = 0; j < n_labels; ++j)
        {
#define logafunc(n) loga[ratings[i].worker * rank + n]
#define cfunc(n) c[n_labels * n + j]
#define dfunc(n, k) ((k == j) ? 0 : d[n_labels * n + k])

          pz[j + ratings[i].image * n_labels] += 
            logprating (ratings[i].rating,
                        logafunc,
                        rank,
                        logbeta[ratings[i].image],
                        cfunc,
                        dfunc,
                        n_labels);
#undef dfunc
#undef cfunc
#undef logafunc
        }
    }

  float q = 0;

  for (unsigned int i = 0; i < n_images; ++i)
    {
      q += safe_exponentiate_normalize (pz + i * n_labels, n_labels);
    }

  return q;
}
